The use of unsaturated polyester polyols is known as stabilization precursors in the production of polymeric polyols, which, in turn, can be used in the manufacturing of cellular polyurethane compounds.
The production of unsaturated polyester polyols using the reaction of alkylene oxides with an acid ester produced by the reaction of an unsaturated acid anhydride with an alkylene oxide polyether polyol is sufficiently disclosed in North American patents U.S. Pat. No. 3,391,092, U.S. Pat. No. 4,014,846, U.S. Pat. No. 4,093,573 and U.S. Pat. No. 4,144,395, which disclose processes to produce unsaturated polyester polyols both in the absence of catalysts and in the presence of catalysts (trialkylamines). North American U.S. Pat. No. 3,374,208 discloses the use of several metal catalysts to obtain unsaturated polyester polyols. North American U.S. Pat. No. 4,550,194 discloses the use of calcium or cobalt naphthenate to produce unsaturated polyester polyols with an acid value lower than 0.5 mg KOH/g.
Nevertheless, the state of the art does not show the form to obtain unsaturated polyester polyols with an unsaturation equal to or less than 0.1 meq/g without significantly reducing the molecular weight of the unsaturated polyester polyols. These unsaturated polyester polyols can be used as precursors for polymeric polyols with improved properties with respect to the viscosity, filterability and particle size which facilitate the manufacturing of cellular polyurethane compounds.